In current communication device systems such as the Global System for Mobile Communications (GSM) radiotelephone system, a SIM card is inserted into a radiotelephone for providing subscriber identification, billing information and other information concerning the operation of the communication device. Before allowing any non-emergency call the radiotelephone must detect a SIM card inserted therein. If no SIM card is detected then no non-emergency calls are allowed. However, in accordance with existing GSM standards, SIM cards need only be operable within a temperature range of −25° C. to 70° C. with occasional peaks up to +85° C. Therefore, a SIM card may not be detected in the radiotelephone when the radiotelephone is located in a temperature environment outside of the normal −25° C. to 70° C. temperature range. Thus, the SIM card is the limiting factor in automotive grade radiotelephone's designed to work from −40° C. to +85° C.
Although it is unlikely that a user and/or communication device would be in an over 70° C. environment, it is quite common in colder climates for a user to be in a less than −25° C. environment, which would prevent their being able to use the radiotelephone, in an emergency or otherwise. For example, a user entering a vehicle utilizing a GSM radiotelephone system in a cold climate during winter may not be able to use their phone. If there is an emergency situation in this case, which can be dangerous given the temperature, it is highly desirable that the radiotelephone work even if the SIM card is inoperable.
The above problem is becoming an increasing concern as more and more GSM systems are being incorporated into onboard Telematics communications systems for vehicles. Existing systems do not address the temperature issues and behave the same as their portable counterparts. For example, in one system an inoperable SIM card will generate an error message, but take no other action in order to recover from the error, regardless of temperature. In this case, the radiotelephone must continually be turned on and off in an attempt to recover. In another system, a controller may recognize that a SIM card is inserted, but if the SIM card is inoperable, the controller will place itself in an endless reset loop. In yet another system, the radiotelephone may immediately switch off if a temperature extreme condition is encountered and the unit is not in the middle of an emergency call. Once the emergency call is ended the unit will then immediately switch off if a temperature extreme condition is still encountered. In all of these prior solutions, there is no controlled recovery mode for returning the radiotelephone to normal service.
What is needed is an apparatus and method to detect those times when a SIM card in a communication device is inoperable due to temperature extremes and affect the means to return the radiotelephone to normal service. It would also be of benefit to allow emergency calling at extended automotive temperature ranges when it is found that the SIM card is inoperable due to temperature extremes. Further, it is desirable to provide this protection with a minimal change of software and hardware.